> Applying CSS in `document_idle` phase would eliminate this. > Actually, just like `scripting.executeScript`, I would say the CSS and JS should be by default injected in `document_idle` phase. I assume you mean `document_start`, right? `document_idle` is the default and corresponds to the "complete" readyState. https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extensionTypes/RunAt
Bug 1846274 Comment 13 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
> Currently the CSS is injected only after the whole message is fully loaded. > This can take few ms, but also many seconds. > This is visible especially when using "Dark mode" extensions (which inverts colors of the messages). > Even with small messages with no remote content, there is visible white flash. More complex emails > full of remote content (like some animated gif) can load for several seconds without the injected CSS. > > Applying CSS in document_idle phase would eliminate this. > Actually, just like `scripting.executeScript`, I would say the CSS and JS should be by default injected in `document_idle` phase. I assume you mean `document_start`, right? `document_idle` is the default and corresponds to the "complete" readyState. https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extensionTypes/RunAt We cannot change the default, but I am trying to support `document_start` and `document_end`.